Flexible nonmetallic electric conduit



H. M. SHORT FLEXIBLE NONMETALLIC ELECTRIC C ONDUIT Nov. 24 1925.

Filed Jan. 30, 1922 Fig". 2..

R C T N E V m Patented Nov. 24, 1925.

PATENT HENRY M. SHORT, OF PENN YAN, NEVJ YORK.

FLEXIBLE NONMETALLIC ELECTRIC CONDUIT.

Application filed January 30, 1922.

To all whom it may concern:

Be it known that I, HENRY M. SHORT, a citizen of the United States ofAmerica, residing at Penn Yan, Yates County, New

York, have invented a new and useful Flexible Nonmetallic ElectricConduit, of

which the following is a specification.

The main object is to provide at a reasonable cost, a substantial tubewhich will meet all of the requirements of the fire underwriters. I havealso sought to provide a construction which can be made on simple andrelatively inexpensive machines. Incidently, I have sought to make asingle wall tube which although very flexible is substantiallynon-extensible and noncollapsible, and yet, may be readily fished.

Figure l is a side view of a fragment of a conduit embodyingimprovements of my invention showing one end uncoated, split and spreadout.

Fig. 2 is a fragmentary transverse section on an exaggerated scale onthe plane of the line 22 of Fig. 3.

is a longitudinal sectional view on an enlarged scale.

The fabric of the tube is made up of a series of longitudinal cords 5surrounded by cii'cuintcrentiuliv extending ribs 6, and a tie 1 1 memberwhich is knitted about the cords and ribs. These'members are assembledin a special form of knitting machine so that the knitted loops draw thetension cords into close contact with the ribs.

Preferably all of the members are of t *isted fibre which can be readilyhandled in a knitting machine. These members When the tension isproperly adjusted sink into each other at the points of crossing so asto produce a con'irmratively smooth interior surface which will notinterfere With fishing the electric wires.

The ribs may conveniently be in the form of a continuous coilsurrounding the tension Serial No. 532,659.

members which are also preferably continuous. The ribs may be somewhatlarger and stiffer or more resilient than the tension members so as togive a maximum rigidity against collapse.

By having the tension members arranged all on one side of the ribs (asdistinguished from being interwoven with the ribs), I secure a maximumdegree of flexibility. Although it is desirable to use longitudinaltension members such as 5, it should be understood that the knittedfabric itself affords substantial longitudinal tensional strength,particularly when the fireproof and waterproof coating 8 has beenapplied. This coating is preferably applied in the form of a hot liquidwhich impregnates the outer Wall and fills up all the outer spacesbetween the members of the tube. The tube is preferably knitted tightlyenough so as to prevent the liquid composition from passing through tothe interior.

I claim:

A sin le wall, flexible, non-metallic electric conduit comprisinglongitudinal tension cord members of fibrous fleizible material, a

stiffer continuous helical coil member formed of fibrous material, a tiemember tightly knitted about said coil and cord members and formed ofsoft fibre and having loops tightly holding portions of said tensioncord members between the adjacent turns of said coil member, saidmembers being embedded in each other at the points of contact, parts ofsaid loops and said tension cord members and said coil member forming asmooth inner surface of said conduit, and a fireproof and waterproofcomposition covering the outside of said conduit and impregnating andstiffening the outer parts of said members and securing said tensioncord members to said helical. coil member.

HENRY M. SHORT.

